The problem arises in the mass production of certain electronic components, for example quartz crystal resonators, which are required in view of their nature to be maintained under vacuum and thus must be placed in supporting containers in such a way to be competely sealed. This sealing must be absolute in nature and must have a life of at least several years. In the case of quartz resonators for instance, even the smallest leaks will bring about an increase in the series resistance of the resonator which finally will no longer oscillate.
In mass production of such components there are many problems to be resolved and in effect the mere fact that the soldering itself must respond to severe criteria implies that the components involved must be brought to the soldering centre by automatic means. It has already been proposed to provide an arrangement including air locks in which a component carrier would be transferred from an air lock into a working chamber and thereafter would exit through a second air lock. The problem here is one of mass production in soldering several hundreds of these components in succession. A component carrier then may take the form of an elongated element or bar provided with cells for holding and retaining the components undergoing sealing, each such component being stepped under a soldering head. In order to maintain such a bar under the necessary vacuum, the working chamber is required to be unusually long. It is in an effort to reduce the dimensions of the apparatus as well as to speed up the entire procedure that the present transfer apparatus has been devised. Herein a positive advantage is secured inasmuch as the working chamber need no longer be twice the length of the component carrying bar. In prior art arrangements in which air locks were not generally applied the working chamber had to be at least twice the length of the component carrying bar and thus at each occasion when the apparatus was loaded a substantial waiting time would accrue in order to achieve the vacuum under which the soldering would then be carried out. In the present apparatus two air locks are provided as well as the working chamber, each of the three chambers being substantially equal to the length of the component carrying bar. Gate type valves are provided between air locks and the working chamber and as well valves are provided at the outer end of the two air locks. Thus, it becomes possible to maintain at all times a partial vacuum within the system and in this way the entire procedure is accelerated. For example, it is always possible to maintain a vacuum of 10.sup.-2 Torr. This is owing to the system of valves and to the two air locks. Transport from an entry air lock into the working chamber and thence into the exit air lock is effected by means of a magnet on each end of the component carrying bar and through the use of external magnets which may operate through the walls of the air locks, these being formed of a material permeable to magnetic lines of force.